Eddy Currents Induction Cooktop (1 Viewer)

[timeflies]

Can someone (FizzyCyst pls help) explain why the answer here is C. I would have thought that it'd be D as high resistance would mean more heat given off due to resistive heating/friction.

 

[Fizzy_Cyst]

The lower the resistance of the pot, the greater the size of the eddy current.

Power loss (I.e heat) is directly proportional to current squared, the greater the current, the greater the heat generated

 

[timeflies]

The lower the resistance of the pot, the greater the size of the eddy current.

Power loss (I.e heat) is directly proportional to current squared, the greater the current, the greater the heat generated

Ahh that makes much more sense, thank you! I was confused as you needed higher resistance for higher heat loss but also needed low resistance for there to be eddy currents, but relating to that equation, it makes sense

 

[Fizzy_Cyst]

Yeah, don't be misled. Some sources say that Iron works well with induction cooktops due to its high resistance, which is incorrect!

The main mechanism via which heat is generated in induction cooktops is magnetic hysteresis, rather than induced eddy currents. Otherwise, Aluminium (which is a far better conductor than iron and its alloys) would be better suited to an induction cooktop due to its lower resistance.

Perhaps look into magnetic hysteresis as it shows you have gone beyond the syllabus, which the markers really want!

 

[Speed6]

Yeah, don't be misled. Some sources say that Iron works well with induction cooktops due to its high resistance, which is incorrect!

The main mechanism via which heat is generated in induction cooktops is magnetic hysteresis, rather than induced eddy currents. Otherwise, Aluminium (which is a far better conductor than iron and its alloys) would be better suited to an induction cooktop due to its lower resistance.

Perhaps look into magnetic hysteresis as it shows you have gone beyond the syllabus, which the markers really want!

Prof. Dr. Fizzy_Cyst

 

[Rhinoz8142]

Yeah, don't be misled. Some sources say that Iron works well with induction cooktops due to its high resistance, which is incorrect!

The main mechanism via which heat is generated in induction cooktops is magnetic hysteresis, rather than induced eddy currents. Otherwise, Aluminium (which is a far better conductor than iron and its alloys) would be better suited to an induction cooktop due to its lower resistance.

Perhaps look into magnetic hysteresis as it shows you have gone beyond the syllabus, which the markers really want!

Really could you do that ?

 

[QZP]

The lower the resistance of the pot, the greater the size of the eddy current.

Power loss (I.e heat) is directly proportional to current squared, the greater the current, the greater the heat generated

I'm still not convinced. The formula you supplied I've seen only apply to transmission lines (unless you have a source that says otherwise).

Using HSC understanding, even if eddy current size increases with decreased electrical resistance, the rate at which that electrical energy is converted to heat decreases because of the decreased electrical resistance (electron collisions)??.

But also taking the alternative: if we instead increase electrical resistance, then there would be minimal eddy current to convert to heat...

Seems like both situations is incorrect :{ I don't like this Q

 

[mreditor16]

I'm still not convinced. The formula you supplied I've seen only apply to transmission lines (unless you have a source that says otherwise).

Using HSC understanding, even if eddy current size increases with decreased electrical resistance, the rate at which that electrical energy is converted to heat decreases because of the decreased electrical resistance (electron collisions)??.

But also taking the alternative: if we instead increase electrical resistance, then there would be minimal eddy current to convert to heat...

Seems like both situations is incorrect :{ I don't like this Q

I was thinking the same..... :/

 

[Fizzy_Cyst]

I'm still not convinced. The formula you supplied I've seen only apply to transmission lines (unless you have a source that says otherwise).

Using HSC understanding, even if eddy current size increases with decreased electrical resistance, the rate at which that electrical energy is converted to heat decreases because of the decreased electrical resistance (electron collisions)??.

But also taking the alternative: if we instead increase electrical resistance, then there would be minimal eddy current to convert to heat...

Seems like both situations is incorrect :{ I don't like this Q

This is true, but collisions between electrons and lattice is not the sole source of heat loss.

http://ecee.colorado.edu/copec/book/slides/Ch12slide.pdf

Slide 38/39

The equation can be used whenever current flows through a conductor. It is a general eqn for power loss

 

[Elise8842]

This is true, but collisions between electrons and lattice is not the sole source of heat loss.

http://ecee.colorado.edu/copec/book/slides/Ch12slide.pdf

Slide 38/39

The equation can be used whenever current flows through a conductor. It is a general eqn for power loss

What if this mc turns into a four mark question asking how did induction cooktop work? Base on our HSC understanding, should we still state that "heat is generated by eddy current in the cooktop made of high resistance metal?"


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